1. Field of the Invention
The present invention relates to stabilized polyoxyalkylene polyether polyol compositions and to their use in the preparation of polyurethane foams. Particularly, the invention relates to certain stabilizer combinations which synergistically enhance the heat and oxidative stability of polyoxyalkylene polyether polyols and inhibit color and/or scorch development in polyurethane foams made therefrom. More particularly, the present invention relates to polyether polyols synergistically stabilized by incorporating therein certain hindered phenolic compositions with certain aromatic amines and optionally including aliphatic and/or aromatic phosphites.
2. Description of the Prior Art
The prior art teaches the use of various hindered phenolic compositions for the stabilization of polyoxyalkylene polyether polyols. U.S. Pat. No. 3,437,694 teaches the use of 2,6-di-t-butyl-4-methylphenol and 2,4-dimethyl-6-t-butylphenol as stabilizers. U.S. Pat. No. 4,007,230 teaches that synergistic antioxidant compositions consisting of certain hindered phenols such as 2,6-di-t-butyl-4-methylphenol and 4,4'-bis-(alpha,alpha-dimethyl-benzyl)diphenylamine are useful for stabilizing polyoxyalkylene polyether polyols against oxidative degradation and preventing scorch in the polyurethane foams prepared from such polyols. U.S. Pat. No. 4,021,385 claims the use of phenols such as 2,6-di-t-butyl-4-methylphenol with 4,4'-bis(alpha,alpha-di-methyl-benzyl)diphenylamine incorporated in polyoxyalkylene polyether polyols which are employed then for the preparation of polyurethane foams. There is no teaching in the prior art of the synergistic effect of employing the combination of hindered phenols of the instant invention.